Internal combustion engines, particularly large diesel engines of the type used in over-the-road trucks, construction equipment, and the like, are frequently difficult to start, particularly in weather conditions where the ambient temperature is 50° F. or lower. To facilitate starting such engines, it has long been the practice to supply a volatile starting fluid, such as ether, to the engine during the initial “cranking” of the engine.
Generally the ether, or other starting fluid, is selectively supplied to the engine intake through use of a control valve having a valve inlet adapted for operative connection to a canister, or other source of the starting fluid, and an outlet operatively connected to the engine intake. Through the years, such control valves, and the systems in which they are utilized have taken many forms. In some approaches, the valve is manually controlled directly by the operator of the vehicle in which the engine is installed, through use of a mechanically linkage and actuating cable. In other prior approaches, control valves have included an electrical solenoid, for actuating the valve in response to electrical signals manually inputted by the operator of the vehicle, or by various types of automatic electronic control systems.
Examples of prior automatic starting fluid dispensing methods, apparatuses and control valves for use therein are provided by U.S. Pat. Nos. 5,839,469, to Burke; 5,388,553, to Burke et al.; 4,774,916, to Smith; 4,202,309, to Burke; 3,960,131, to Davis; and 3,750,639, to DiGirolamo.
None of the prior approaches to providing starting fluid for an engine has proved to be entirely satisfactory, however. An improved method and apparatus, and particularly an improved control valve is desirable.
Some prior control valves do not include provisions for positively closing off the gas pathway between the valve inlet and outlet, thereby creating the potential for a vacuum leak through the control valve, when the inlet of the control valve is not presently connected to the source of starting fluid. Such a circumstance may occur, for instance, where starting fluid is provided from a detachable canister, of the type widely utilized in the industry for supplying ether, or other starting fluids to an engine. The Burke '469 and '309 patents do disclose control valves having seal elements for precluding such a vacuum leak, when the canister is not attached to the valve, but the particular seal construction and operations disclosed necessitate a fairly complex configuration for a number of the valve components, which therefore and desirably increases the cost and reduces the reliability of valves constructed in accordance with the teachings of Burke.
For control valves utilizing a solenoid-powered actuator, experience has shown that, far-and-away, the component of the control valve that fails most frequently is the electrical coil of the solenoid. To date, no prior control valve has provided the capability for removal and replacement of the electrical coil of the solenoid, while the remainder of the control valve remains operatively connected to the engine and/or the canister, or other source of starting fluid. Considerable improvement would be provided by a control valve apparatus and/or method allowing the electrical coil of the solenoid to be replaced, without disturbing the remainder of the control valve, and in particular without having to disconnect operative connections between the valve outlet and the engine, and/or, removal of the canister or disconnection from the source of ether or starting fluid from the valve inlet.
Many starting fluid control valves and systems incorporate a metering device into the operative connection between the outlet of the control valve and the engine. The metering device typically includes one or more orifices of small size (having an effective diameter of 0.005 to 0.008 inches, for example) for regulating the flow of starting fluid into the engine intake to a pre-determined, desired, value. In some systems, this metering device is a separate component, inserted into tubing connecting the valve outlet to the engine. Having the metering device exposed in such interconnecting tubing, rather than being located internal to the control valve, is typically undesirable, in that it increases complexity and cost of the installation, and makes tampering with the metering device more probable, than in prior approaches where the metering device is incorporated into the valve. Generally speaking, therefore it is desirable to have the metering device incorporated into the control valve, rather than having it be a separate component in a starting fluid injection system.
Another problem encountered in prior starting fluid injection systems and control valves, is that the small orifices in the metering element can become blocked with particulate matter generated during operation of the control valve, or from environmental contamination. This is particularly a problem where no provision is made for blocking off the flow pathway through the control valve when the canister is not in place, such that engine vacuum can draw ambient air, which may include smoke, dust, moisture, or other particulate matter through the control valve while the canister is not present. Even where provisions are made for positively closing off the gas pathway through the control valve when the canister is not present, it must be expected that at least a small amount of particulate matter from the outside environment will make its way into the gas pathway, even if a new canister is immediately installed when an old one is removed. Such ambient particulate matter, in addition to any particulate matter which may be present inside of the starting fluid canister, or generated by operation of the control valve during its lifetime, can plug the orifices in the metering device.
The Burke '469 patent discloses locating an orifice defining element in an exit port of a control valve, and providing a single-stage filter element just upstream from the orifice defining element. The configuration and retention provisions of the orifice defining element and single-stage filter of Burke '469 result in a configuration which is overly complex to manufacture and which is not conducive to minimizing restrictions in gas flow through the valve, nor is the arrangement of Burke '469 readily accessible for cleaning or replacement of the filter, and/or changing of the orifice defining element to match various applications of the valve.
As a final note, by way of background, prior control valves, used in starting fluid injection systems and methods, have been more complex to manufacture than is desirable, generally having a number of parts requiring that complex machining and assembly techniques be utilized, to ensure proper operation of the control valve.
What is needed therefore, is an improved method and apparatus for supplying starting fluid to an engine, and in particular, an improved control valve for use in such systems, addressing one or more of the problems or providing one or more of the desired attributes set out above.